Listerial brainstem encephalitis is a rare disease. Only 62 cases have been reported previously; all were in adults, only 8% of whom were immunosuppressed. The disease has a characteristic biphasic course: a nonspecific prodrome of headache, nausea or vomiting, and fever lasting for several days is followed by progressive asymmetrical cranial-nerve palsies, cerebellar signs, hemiparesis or hypesthesia, and impairment of consciousness. Neck stiffness was initially present in only 55% of the cases described thus far. Studies of cerebrospinal fluid often revealed only mild abnormalities. Cultures of cerebrospinal fluid and blood were positive in 41% and 61% of cases, respectively. Respiratory failure occurred in 41% of cases. Initial computed tomography of the brain often gave normal results; magnetic resonance imaging better demonstrated brainstem abnormalities. Overall mortality was 51%. All untreated patients died. When treatment with ampicillin or penicillin was initiated early, the rate of survival was > 70%; however, neurological sequelae developed in 61% of survivors.